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This article was originally featured in the edition: Volume 24 Issue 6

Lasers: Excelling With Extreme Asymmetry

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Chip designs that exploit extreme triple asymmetry equip diode lasers with both efficiency and power by Paul Crump from FBH Berlin

In advanced industrial laser systems, which have uses that include the cutting of metals, highpower diode lasers are the source of all optical energy. In these systems, a highly intense beam is formed by either combining the optical output of many diode lasers, or by using many of them to pump a solid state or fibre laser.

Diode lasers are widely used for this task, because they are the most efficient technology for converting electrical input energy into application-ready light. However, given their key role in industrial laser systems, even higher efficiencies are preferred, along with an increase in the maximum output power. Succeeding on both these fronts requires a good understanding of the physical effects that limit performance, because this can help to guide the development of ever more sophisticated and higher performing device designs. Such efforts should focus on high-power diode lasers that are grown on GaAs substrates and emit in the 900 nm to 980 nm wavelength range, because these are the highest performing devices, and the ones in greatest demand from industry.

At the FBH Berlin, our team has devoted many years to realising a greater understanding of this class of laser, and increasing its performance. GaAs diode lasers are a very mature, highly commercially successful technology. In spite of this, there is still much to learn and substantial improvements are still possible.

Recently, we introduced sophisticated epitaxial layer structures that have increased the power and efficiency of this infra-red source. These groundbreaking devices employ extreme triple asymmetrical designs that precisely manipulate the optical field within the chip.